Part Two..
Continued from yesterday.
Offensive unit
The role of the offensive unit is to advance the football
down the field with the ultimate goal of scoring a touchdown.
The offensive team must line up in a legal formation before
they can snap the ball. An offensive formation is considered illegal if there
are more than four players in the backfield or fewer than five players numbered
50-79 on the offensive line. Players can temporarily line up in a position
whose eligibility is different from what their number permits as long as they
immediately report the change to the referee, who then informs the defensive
team of the change. Neither team's players, with the exception of the snapper,
are allowed to line up in or cross the neutral zone until the ball is snapped.
Interior offensive linemen are not allowed to move until the snap of the ball.
The main backfield positions are the quarterback,
halfback/tailback and fullback. The
quarterback is the leader of the offense. Either he or a coach calls the plays.
Quarterbacks typically inform the rest of the offense of the play in the huddle
before the team lines up. The quarterback lines up behind the center to take
the snap and then hands the ball off, throws it or runs with it. and often are
not used in passing situations.
The offensive line
consists of several players whose primary function is to block members
of the defensive line from tackling the ball carrier on running plays or
sacking the quarterback on passing plays. On either side of the center are the
guards, while tackles line up outside of
the guards.
The principal receivers are the wide receivers and the tight ends . Wide receivers line up
on or near the line of scrimmage, split outside of the line. The main goal of
the wide receiver is to catch passes thrown by the quarterback,
The defensive backfield, often called the secondary,
consists of cornerbacks and safeties .
Safeties are themselves divided into free safeties and strong safeties .
The positions specific to punt plays are the punter, long
snapper, and gunner. The long snapper snaps the football directly to the
punter, who then drops and kicks it before it hits the ground. Gunners line up
split outside of the line and race down the field, aiming to tackle the punt
returner - the player that catches the
punt.
Scoring
In American football, the winner is the team that has scored
the most points at the end of the game. There are multiple ways to score in a
football game.
The touchdown, worth six points, is the most valuable
scoring play in American football. A touchdown is scored when a live ball is
advanced into, caught in, or recovered in the end zone of the opposing team. If
it is scored by what would normally be a touchdown, it is called the two-point
conversion In general, the extra point is almost always successful in
professional play and is only slightly less successful at amateur levels, while
the two-point conversion is a much riskier play with a higher probability of
failure; accordingly, extra point attempts are far more common than two-point
conversion attempts. After a PAT attempt or successful field goal the scoring
team must kick the ball off to the other team. A safety is scored when the ball
carrier is tackled in his own end zone. Safeties are worth two points, which
are awarded to the defense.
Field and equipment
Football games are played on a rectangular field that
measures long and wide. Lines marked along the ends and sides of the field are
known respectively as the end lines and side lines, and goal lines are marked
inward from each end line. Weighted pylons are placed on the inside corner of
the intersections of the goal lines and end lines.
White markings on the field identify the distance from the
end zone. Inbound lines, or hash marks, are short parallel lines that mark off
increments. Yard lines, which run the width of the field, are marked every . A
one yard wide is placed at each end of the field; this line is marked at the
center of the two-yard line in professional play and at the three-yard line in
college play. Numerals that display the distance from the closest goal line in
multiples of ten are placed on both sides of the field every ten yards.
Goalposts are at located at the center of the plane of each
of the two end lines. The crossbar of these posts is ten feet above the ground, with vertical uprights at
the end of the crossbar 18 feet 6 inches
apart for professional and collegiate play and 23 feet 4 inches apart for high school play.
The football itself is an oval ball, similar to the balls
used in rugby or Australian rules football. At all levels of play, the football
is inflated to to pounds per square inch
and weighs 14 to 15 ounces ; beyond that, the exact dimensions vary
slightly. In professional play the ball has a long axis of 11 to inches, a long
circumference of 28 to inches, and a short circumference of 21 to inches, while
in college and high school play the ball has a long axis of to inches, a long
circumference of to inches, and a short circumference of to inches. High school
football games are 48 minutes in length with two halves of 24 minutes and four
quarters of 12 minutes. The two halves are separated by a halftime period, and
the first and third quarters are also followed by a short break. Prior to the
start of the game, the referee and team captains for each team meet at midfield
for a coin toss. The visiting team is allowed to call 'heads' or 'tails'; the
winner of the toss is allowed to decide from between choosing whether to
receive or kick off the ball or choosing which goal they want to defend, but
they can also defer their choice until the second half. The losing team, unless
the winning team decides to defer, is allowed to choose the option the winning
team did not select, and receives the option to receive, kick, or select a goal
to defend to begin the second half. Most teams choose to receive or defer,
because choosing to kick the ball to start the game would allow the other team
to choose which goal to defend. Teams switch goals following the first and
third quarters. If a down is in progress when a quarter ends, play continues
until the down is completed.
Games last longer than their defined length due to play
stoppages - the average NFL game lasts slightly over three hours. Time in a
football game is measured by the game clock. An operator is responsible for
starting, stopping and operating the game clock based on the direction of the
appropriate official. A separate clock, the play clock, is used to determine if
a delay of game infraction has been committed. If the play clock expires before
the ball has been snapped or free-kicked, a delay of game foul is called on the
offense. The play clock is set to 40 seconds in professional and college
football and to 25 seconds in high school play or following certain
administrative stoppages in the former levels of play.
Advancing the ball and downs
There are two main ways that the offense can advance the
ball: running and passing. In a typical play, the quarterback calls the play,
and the center passes the ball backwards and under his legs to the quarterback
in a process known as the snap. The quarterback then either hands the ball off
to a back, throws the ball or runs with it himself. The play ends when the
player with the ball is tackled or goes out of bounds, or a pass hits the
ground without a player having caught it. A forward pass can only be legally
attempted if the passer is behind the line of scrimmage.
The offense is given a series of four plays, known as downs.
If the offense advances ten or more yards in the four downs, they are awarded a
new set of four downs. If they fail to advance ten yards, possession of the
football is turned over to the defense. In most situations, if the offense
reaches their fourth down they will punt the ball to the other team, which
forces them to begin their drive from further down the field; if they are in
field goal range, they might also attempt to score a field goal. On television,
a yellow line is electronically superimposed on the field to show the first
down line to the viewing audience.
Kicking
There are two categories of kicks in football: scrimmage
kicks, which can be executed by the offensive team on any down from behind or
on the line of scrimmage, and free kicks. The free kicks are the kickoff, which
starts the first and third quarters and overtime and follows a try attempt or a
successful field goal, and the safety kick, which follows a safety.
On a kickoff, the ball is placed at the 35-yard line of the
kicking team in professional and college play and at the 40-yard line in high
school play. The ball may be drop-kicked or place-kicked. If a place kick is
chosen, the ball can be placed on the ground or on a tee, and a holder may be
used in either case. On a safety kick, the kicking team kicks the ball from
their own 20-yard line. They can punt, drop-kick or place-kick the ball, but a
tee may not be used in professional play. Any member of the receiving team may
catch or advance the ball, and the ball may be recovered by the kicking team
once it has gone at least ten yards and has touched the ground or has been
touched by any member of the receiving team.
The three types of scrimmage kicks are place kicks, drop
kicks, and punts. Only place kicks and drop kicks can score points. because the
pointy shape of the football makes it difficult to reliably drop kick. Once the
ball has been kicked from a scrimmage kick, it can be advanced by the kicking
team only if it is caught or recovered behind the line of scrimmage. If it is
touched or recovered by the kicking team beyond this line, it becomes dead at
the spot where it was touched. The kicking team is prohibited from interfering
with the receiver's opportunity to catch the ball, and the receiving team has
the option of signaling for a fair catch. This prohibits the defense from
blocking into or tackling the receiver, but the play ends as soon as the ball
is caught and the ball may not be advanced.
Final part coming in tomorrow's blog.
Tipster Street.
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